Multi-leaf torsion spring for closing a breechblock



July 31, 1956 M. J. ENGEL ETAL 2,755,635

MULTI-LEAF TORSION SPRING FOR CLOSING A BREEICHBLOCK Filed Dec. 21, 19544 Sheets-Sheet. 1

INVENTOR. Marvin J .Enge. l wan 11 Hngpss Jul-1n B-5fl1e.ry

wi iiwwazaw July 31, 1956 M. J. ENGEL HAL 2,756,635

MULTI-LEAF TORSION SPRING FOR CLOSING A BREECHBLOCK Filed Dec. 21, 19544 Sheets-Sheet 2 INVENTOR. Marvin J- Engel [Ivan llHcn pasl John E15ille.ry

R TTOENE'YG 4 Sheets-Sheet 3 M. J. ENGEL ETAL MULTI-LEAF TORSION SPRINGFOR CLOSING A BREECHBLOCK July 31, 1956 Filed Dec. 21, 1954 5 Y m1 5 TaN N 5 z fi m m r J. H

MEIVII'L Swan 1] Hal: JCIhTL ELElxll BY 9%5M1QMV QMQLW- July 31, 1956 M.J. ENGEL ETAL MULTI-LEAF TORSION SPRING FOR CLOSING A BREECHBLOCK 4Sheets-Sheet.

Filed Dec. 21, 1954 Mm M15 5 MAP. Wm Vnma d mE u 1T Hwm n m Wm Mob 52,756,635 Patented July 31, 1956 MULTI-LEAF TORSION SPRING FOR CLOSING ABREECHBLOCK Marvin J. Engel, Albany, Owen D. Hoopes, Latham, and John B.Sillery, Albany, N. Y., assignors to the United States of America asrepresented by the Secretary of the Army Application December 21, 1954,Serial No. 476,861 3 Claims. (Cl. 8917) The invention described hereinmay be manufactured and used by or for the Government for governmentalpurposes without the payment of any royalty thereon.

This invention relates to breech mechanisms for firearms and moreparticularly to the spring means for closing the breechblock memberthereof.

In designing those guns which are to be mounted in combat vehicles suchas tanks, the limited space available inside of the turrets necessitatesa continuing effort to reduce the size of the weapons withoutsacrificing fire power.

One of the most space consuming of the components of a cannon locatedwithin a turret is the breech mechanism which requires cooperatingmechanical linkages, springs and arrangements of components to performits function of opening the chamber of the gun tube for the extractionof a spent cartridge case and the loading of a live round and of closingthe chamber for the firing of the round.

In virtually all cannons used in tanks, the breechblocks are opened byusing the energy of gun recoil or counterrecoil to rotate a crank whichlowers the breechblock to an open position and at the same time ejectsthe spent cartridge case and energizes a spring device linked to thebreechblock. The spring retains the stored energy until the breechblockis released for closing by a newly chambered round which trips theextractors holding the breechblock in open position, at which time theautomatically released energy of the spring closes the breechblock tomake the gun ready for fire.

Many types of springs have been used for this purpose. The one mostcommonly used is a straight helical compression spring, but thisarrangement utilizes a large amount of space because of the separatehousing required for the spring and the cooperating linkages locatedalong side the breech. Clock springs have also been used, but again thespace ratio of spring to breech is on the high side. Torsion helicalsprings of both square and round highly stressed wire have been usedsuccessfully for reducing the amount of occupying space per unit ofenergy, but the space gain is accomplished through the use of criticalmaterial which in applications for cannons of larger caliber than 75 mm.is prohibitive. The use of lower strength wire means that workingstresses must be lowered, consequently the spring increases in size andits advantage in compactness becomes lessened.

A solid bar of either round or rectangular cross-section enables a largeamount of energy to be stored in a small space when subject to angularmovement, but the angular movement allowable before plastic flow startsis much too small to effectively close the breech of a gun.

It is the object of this invention to provide for the breech mechanismof a firearm a torsional spring device for closing the breechblock unitwhich has the advantage of the space gain provided by a torsional barspring, yet may be operated through an angular movement suflicient toclose the breechblock without being over-stressed, and

the further advantage of being formed from readily available,non-critical material.

It is another object of this invention to provide for the breechmechanism of firearms a space saving spring for closing the breechblockof a firearm which is comprised of a plurality of thin leaves stacked toform a torsional spring of rectangular cross-section. Thus, each leafacts as an independent torsion bar, subject to torsional load about itslongitudinal axis of symmetry, and by this distribution of load thestress in the torsional spring for any given angular twist is reduced.

It is a further object of this invention to provide for the breechmechanism of firearms a torsional bar spring for closing the breechblockwhich is adjustable to any desired torsional moment.

It is a still further object of this invention to provide for the breechmechanism of firearms a spring for closing the breechblock which ismountable within the operating shaft and so does not occupy any space inaddition to the designed configuration of the operating components andwhich provides a more nearly symmetrical breech mechanism.

The specific nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawings in which:

Fig. l is a view showing the rear end of a cannon;

Fig. 2 is an enlarged view taken along line 2-2 of Fig. 1;

Fig. 3 .is an enlarged rear end view of the cannon partially broken awayto show the angular relationship of the breechblock closing spring whenthe breechblock is in open position;

Fig. 4 is an exploded perspective view of the breechblock operatingmechanism;

Fig. 5 is an enlarged view taken along line 5-5 of Fig. 1;

Fig. 6 is an enlarged side view showing the operating crank at point ofengagement with the ejector cam during counterrecoil of the cannon;

Fig. 7 is a view taken along line 7-7 of Fig. 6;

Fig. 8 is an enlarged side view showing the breechblock operated to openposition by the engagement of the operating crank with the ejector camduring counterrecoil of the cannon;

Fig. 9 is a view taken along line 99 of Fig. 8

Fig. 10 is an enlarged fragmentary view showing the ejector cam innormal position in relationship to the gun mount;

Fig. 11 is a view similar to Fig. 10 but showing the ejector cam biasedinwardly by the operating crank during recoil of the cannon;

Fig. 12 is an enlarged cam; and

Fig. 13 is an enlarged perspective exploded view of the adjustingdevice.

Shown in the figures is a breech mechanism of a slide block cannonincluding a breech ring 12 and a breechblock 14 mounted for slidablemovement therein on ways (not shown). Depending from the bottom of brechring 12 is a left lug 18 and a right lug 20 spaced laterally therefrom.Right lug 20 is provided with a bore 22 which is counterbored, as notedat 23, to rotatably receive an adjustor member 24 having a cylindricalportion 26 received within such counterbore and a larger diameterportion 28 which engages the right side of such lug. Extending throughadjustor member 24, symmetrical with the axisthereof, is a rectangularopening 32, which is chamfered, as noted at 33, at the end inside ofportion 26. 'A set screw 34 is threadably mounted through right lug 20to be received by an annular groove 36 around portion 26 wherebyadjustor member 24 is rotatable in perspective view of the ejector"rnent. Aptunger 27 is slidably mounted in "breech ring 12 in back ofportion 28 and is biased against such portion by a coil spring 30.Plunger.27 is receivable by a cooperating notch '31 in portion 28 whichnotch is. provided with aplurality of step portions asbest shownin'Fi'g. 13

*to provide the means for selectively adjusting the rotatable positionof 'adjustor member 24.

Left lug 18 is'bored, as -noted at 37, to receive a cylindfi'c'al shaft38having a bearing portion 42 rotatably received by'such boreand areduced diameter axle portion 40 which =extendsffromsuch bearing portionto be 'rotatablyreceive'd'bybore 22. The end of bearing portion 42adjacent axle portion 40 is cut back to form a semi-annular recess 46for receiving a .key portion 'as "hereinafter noted. Shaft 38 extendsbeyond left lug 18 andprovidedon 'suchexte'nding' portion isan'opera'ting 'cr'ank 48h'aving an integral hub 50' which is spaced fromthe adjacent side of left lug 18 "by a cylindrical flange 'porti'on'52.A' set screw 54 mounted threadably through left'lug "18 is received byan annular groove 56 around be'aring'portion "42 to secureshaft 38against lateral displacement while being rotatable.

"Extending radially from 'hub50 are a protruding portion'58 and anintegral arm 60. A stud 62 extends laterally outward from arm 60 to beengageable during counterrecoil of breech ring 12 with a conventionalejector cam "64mounted on a gun m'ount66 for rotation of shaft '38.Ejector ca1n*64, of conventional design and operation, is spring-biasedoutwardly from mount to an operating crank engaging p'osition'by acooperating'spring 65, whereby stud 62, during the recoil portion of theoperating cycle, engageably actuates such cam inwardly, -to ridethereover. An operating handle 68 is rotatably mounted on flange portion52 and is provided with a p1unger70 receivable by a radial "slot '72in'protruding portion 58 to engage such handle to shaft 38 when manualoperation thereof is desired.

Mounted on axle portion '40 is a breechblock crank 74 having a hubportion 76, which is bored as noted at 78 to receive such axle portion,and an arcuate arm portion 3 80- extending therefrom. A semiannular keyportion 82 projects from hub portion 76 to mate with recess 46 wherebybreechblock crank 74 is engaged for unitary rotation'with shaft 38' andis arranged to extend from shaft 38 in approximately the same directionas operating crank 48. A hollow cylindrical spacer 84 is mounted on axleportion 40 between right lug 20 and breechblock crank 74 for maintainingkey portion 82 thereon in recess 46. Extending laterally through thefree end of arm 80 is a 'cross-head-pivot pin 86 which is mountedtherein to extend beyond both sides of such arm, as noted at 88.

Rotatably mounted on extending portions 88 of pin 86 -is a pair'ofcylindrical cross-heads 90 which are slidably received in apair1ofdiagonal grooves 92' in breechblock 14. Whereby, rotation ofshaft'38 causes breechblock "crank 74 to camrningly raise suchbreechblock to a close position or to lower such breechblock to an openposition. Extending'into shaft 38 from the end of axle portion 40thereof is an axial hole 94 which is terminated by a rectangular mouthportion 96 symmetrical therewith.

Extending through mouth portion 96 and opening 32 in adjustor member 24is a'tor'sional-spring 98 of rectangular cross-section which iscomprised of a plurality of stacked spring leaves 99. Mouth portion 96and opening 32 are so dimensioned that the wallsthereof adjacent the topand bottom ones of the stacked spring leaves 99 are in close engagementtherewith with clearances provided between the edges of such springleaves and the walls of suchmouth portion and opening. -A driving pin100 is mounted-diametrically through base-portion 50 of operatingcrank-48 to'passthrough aligned cylindrical holes 102-provide'd in oneendof leaves'99. A retaining pin 3504 is slid-ably mounted diametricallythrough portion 2610f adjuster. member'24 to pass through alignedelon-"seat itself therein.

Rotation of operating crank 48 by the engagarnent of stud 62 withejector cam 64 rotates shaft 38 to lower breechblock 14 to openpositionand at the same time twists torsional spring 98 to store energy thereinfor closing such breechblock. The elongations of holes 106 permitlongitudinal displacement of leaves 99 when twisted and the clearancesbetween the edges of spring leaves 99 and the adjacent walls of mouthportion 96 and opening 32 permit angular displacement'of such leavesabout pin 100 and retaining pin 104, as best noted in Fig. 9 due to thehelix angle produced when such spring leaves are twisted. Thus, thereisiniparted to spring 98 as near a true torsional load as is possible.Four equally spaced holes 108 are provided in the outer face of adjustermember 24 to permit the use of a conventional spanner wrench'for turningsuch adjustor memher to adjust the preload of torsional bar spring 98and thereby assure the closing of breechblock 14 when releasedfrom openposition. Such adjustment is possible through the cooperation ofplunger'27 with the step portions 35 of notch 31 which are arranged tobecome progress'ively of lesser'depth in'the direction which spring 98applies force to shaft '38 for raising'breechblock 14 to blockingposition. 'To increase the preload in spring '98, adjustor member 24isrotated by a spanner in the direction of the applied force of suchspringuntil the 'nextone of the step portions -35 aligns with plunger 27which, through the bias of spring 30, will automatically To back-off thepreload, plunger 27 is depressed a sufficient lateral distance to clearthe undesired one of the step-portions 35 whereby the preload in spring98 will automatically rotate adjuster member 24 to engage the nextshallower one of the step portions 35 with such plunger.

Operation .such stud to ride over such cam. During the ensuingcounterrecoil of breech ring 12, stud 62 engages the now outwardlyprojecting rear end of ejector cam 64 whereby operating crank 48 isturned, rotating shaft38 which is integral therewith.

Rotation of shaft 38 causes simultaneousrotation of breechblock crank 74.which is engaged for simultaneous rotation therewith by the engagementof key portion 82 of such breechblock crank with recess 46 in bearingportion 42 of such shaft. Whereby, cross-heads are moved along grooves92 in breechblock 14 during rotation of breechblock crank'74 tocamniingly lower such breechblock in breech ring 12 to open position.When breechblock 14' is in open position, a pair of conventionallyoperating extractors (not shown), which have expelled the spentcartridge case from the cannon during the opening of such breechblock,lock such'breechblock in the open position.

During rotation of shaft same endfof spring 98 received'by mouth portion96 'ofsuch shaft is turned, but as the opposite end of the spring isheld against turning by opening 32 in 'adjustormember 24- such springand the spring leaves 99 thereof are twisted to store energy therein.

.a simple and compact spring device for closing the breechblock ofcannons which .does not occupy any space therein in addition to thedesigned configuration of the operating components and which is easilyadjusted to any desired torsional movement.

Although a particular embodiment of the invention has been described indetail herein, it is evident that many variations may be devised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.

We claim:

1. In a cannon having a breech ring with a breechblock mounted thereinfor slidable movement between an open position and a closed position, ashaft mounted for rotatable movement in the breech ring, crank meansmounted to said shaft for camming cooperation with the breechblock foractuation thereof between the open and close positions, an adjustormember mounted for rotatable movement in the breech ring, said adjustormember being axially aligned with said shaft and adjacent one endthereof, said shaft being provided with a bore introduced into the endthereof adjacent said adjustor member, said bore being terminated by arectangular mouth portion, said adjustor member being provided with arectangular opening similar to said mouth portion, a torsional spring ofrectangular cross-section mounted in said bore with the ends thereofbeing received by said mouth portion and said opening, a drive pinmounted through said shaft and a mating circular hole through saidspring for anchoring said spring to said shaft, a retaining pin mountedthrough said adjustor member and an elongated hole in said spring, saidelongated hole providing for linear displacement of said spring whentwisted, and a plunger resiliently mounted in said breech ring forcooperation with a stepped recess in said adjustor member to selectivelyposition said adjuster member for adjustably preloading said spring toassure actuation of the breechblock thereby to the close position.

2. The combination as defined in claim 1 wherein said torsional springcomprises a plurality of stacked spring leaves.

3. The combination as defined in claim 1 with clearances provided insaid mouth portion and said opening for the angular displacement of saidspring leaves when twisted.

References Cited in the file of this patent UNITED STATES PATENTS422,838 Rostel Mar. 4, 1890 72,462,920 Summerbell et a1. Mar. 1, 19492,491,539 Windham Dec. 20, 1949

